#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
int countDiffChar(char* str) {
	assert(str);
	size_t len = strlen(str);
	char* temp = malloc(sizeof(char) * len);
	int count = 0;
	int k = 0;
	for (int i = 0; i < len; i++) {
		if (str[i] >= 0 && str[i] <= 127) {
			int flag = 1;
			for (int j = 0; j < count; j++) {
				if (temp[j] == str[i]) {
					flag = 0;
					break;
				}
			}
			if (flag) {
				temp[k++] = str[i];
				count++;
			}
		}
	}
	return count;
}
int main() {
	char* str = malloc(sizeof(char) * 500);
	scanf("%s", str);
	printf("%d", countDiffChar(str));
	return 0;
}